hibernate/hibernate-orm · error · SchemaManagementException

Illegal state : writer null - not prepared

Error message

Illegal state : writer null - not prepared

What it means

ScriptTargetOutputToFile creates its FileWriter lazily in prepare() and nulls it in release(); writer() throws this SchemaManagementException when a write is attempted while the writer is null — i.e. before prepare() or after release(). It is a lifecycle-contract violation inside the script-target plumbing; stock hbm2ddl calls prepare/write/release in order, so users normally hit it only through custom schema tooling.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/tool/schema/internal/exec/ScriptTargetOutputToFile.java:59

		this.append = append;
	}

	/**
	 * Constructs a ScriptTargetOutputToFile instance,
	 * the bytes will be written to the end of the file rather than the beginning
	 *
	 * @param file The file to read from
	 * @param charsetName The charset name
	 *
	 */
	public ScriptTargetOutputToFile(File file, String charsetName ) {
		this(file, charsetName, true);
	}

	@Override
	protected Writer writer() {
		if ( writer == null ) {
			throw new SchemaManagementException( "Illegal state : writer null - not prepared" );
		}
		return writer;
	}

	@Override
	public void prepare() {
		super.prepare();
		this.writer = toFileWriter( this.file, this.charsetName, append );
	}

	@Override
	public void release() {
		if ( writer != null ) {
			try {
				writer.close();
			}
			catch (IOException e) {
				throw new SchemaManagementException( "Unable to close file writer : " + e );

View on GitHub (pinned to fad1729dce)

Solutions

1. Call prepare() before any write and release() exactly once at the end — mirror SchemaExport's ordering.
2. Never reuse a ScriptTargetOutputToFile after release(); construct a fresh instance for each export run.
3. If this surfaces during plain hbm2ddl with no custom code, upgrade hibernate-core — lifecycle sequencing bugs were fixed in patches.

Example fix

// before: writing before/outside the lifecycle
ScriptTargetOutput out = new ScriptTargetOutputToFile( file, null );
out.write( "create table ..." ); // IllegalStateException-style failure

// after: explicit lifecycle
out.prepare();
out.write( "create table ..." );
out.release();

try {
    target.prepare();
    target.write( ddl );
}
finally {
    target.release(); // release() must run even if write fails, so state is clean for a fresh instance
}

When it happens

Trigger: Calling write() on a ScriptTargetOutputToFile without calling prepare() first; reusing the same target for a second export after release() has run (release() sets writer=null); custom SchemaManagementTool/GenerationTarget code orchestrating the target lifecycle out of order.

Common situations: Custom integrations that build their own GenerationTargets; interrupted schema generation where release() already executed and a later phase tries to write again; copies of Hibernate examples that skip prepare().

Related errors

• Writing to script was requested, but no script file was spec
• The ClassLoaderService cannot be reused (this instance was s
• No child ServiceRegistry registrations found
• Can't reactivate an active registry
• Should not register strategies during shutdown

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/d2e3cf670ec32201. Report an issue: GitHub.